The setting or laying of conduits and pipeline on a selected grade line has traditionally involved a generally slow and relatively complicated procedure. In particular, customarily, a survey is completed for the conduit or pipe system whereby, for example with regard to sewer pipe, manholes are marked off every 350 to 400 feet. Traditional procedures also dictate that batterboards then be set at distances of approximately 25 to 50 foot intervals, and a chalk line is strung across the batterboards to establish a line of reference along which the pipe is to be layed. The batterboards are set at such a height that a line passing through the batterboard sights will be above the highest point of the terrain between two adjacent manholes.
The distance between the flow line of the conduit or pipe to be layed and the chalk line reference is thereafter determined to fix the grade. This procedure requires a crew including a pipesetter and an operator of a gauging pole which extends from the line of reference to the top of a section of pipe being layed. The gauge pole must be kept in vertical alignment to properly gauge the grade. Computations are made by the pipesetter depending upon information relayed to him by the gauge pole operator, and the fine grading for the setting of the pipe is done manually by placing gravel and/or dirt under the pipe where the trench has been cut too deep, and by removing soil or gravel from beneath the pipe where the trench is not deep enough. This system is obviously subject to relatively wide fluctuations in accuracy of the finished pipe flow line depending upon the skill and attention of the crew. This method also has obvious limitations on the amount of conduit or pipe which can be layed in a given time period.
A variety of methods and devices have been utilized in the prior art to attempt to improve on the batterboard-chalk line method of fixing grades and laying pipe. For example, in U.S. Pat. No. 3,116,557, which issued Jan. 7, 1964 to J. Trice, Jr., a lightbeam is used as the line of reference for laying sewer pipe, and a projector is placed at the manhole site for passing a lightbeam through the pipe to be layed. A target carrier is attached at the distal end of the section of pipe being layed, and a pair of handles is provided to assist the worker in moving the pipe during alignment procedures. The light is sent through the pipe at an angle determined by the use of standard optical equipment such as a transit and prism located above the manhole. The target carrier fits over the end of the pipe being layed and an operator sets the grade by reference to the position at which the light strikes the target. The Trice method and apparatus is relatively complex and inconvenient in use, and has proven to be insufficiently accurate to ensure reliable results.
In U.S. Pat. No. 3,314,068, which issued to A. Verive on Apr. 11, 1967, a grading method is shown as utilizing a signal producing device which transmits a signal to a receiving device mounted on a gauge pole placed along the flow line of a pipe being layed. While the Verive method and apparatus attempted to reduce the cost of pipe aligning devices and to increase the efficiency of the operation, it relied upon manual alignment of the pipe with fine grading done by hand. For fine grinding, gravel and/or dirt would be pulled under the pipe where the trench was too deep, or the pipe was lifted and additional soil removed where the bottom of the trench was high. A related method for laying pipe is shown in U.S. Pat. No. 3,631,601, which issued to L. McNulty on Jan. 4, 1972. The McNulty reference requires mounting of a laser beam projector in the first pipe section which has been preset along the desired pipeline and grade by conventional surveying techniques. Alignment of subsequent lengths of pipe is accomplished by the same manual methods, with reference to a laser beam target mounted in the pipe section to be aligned. Similar laser beam alignment targets and methods for aligning pipes with laser beams are set forth in U.S. Pat. Nos. 3,907,435 and 3,599,336.
While these attempts to improve upon the tedious and time consuming conventional techniques utilizing batterboards set on line by use of a transit have had varying degrees of success, each relies on a substantial amount of manual labor to align the pipe and to properly set the grade thereof. Additionally, none of the methods and devices heretofore available provide preliminary support for the length of conduit being aligned during initial backfilling procedures. Each of these previously available methods and devices also require a relatively substantial amount of training for operators and laborers utilizing the systems, which can substantially add to the inefficiencies and costs involved in pipelaying operations where labor force turnover rates are relatively high.
Consequently, while there have been a variety of prior art attempts to improve on the conventional methodology utilized to fix grades and set conduit and pipe, heretofore there has not been a tool adapted for aligning and preliminarily supporting a length of pipe to be layed, which is simple in construction and operation, inexpensive, and reliably accurate in use.